The present invention relates to a method of installing furnace walls of a boiler, more specifically a method of installing a furnace wall of a boiler suitable for constructing a large-scale boiler such as one for a thermal power plan.
FIG. 24 shows the exemplary side view of the schematic diagram of coal fired large-scale boiler for a thermal power plant. A boiler 1 chiefly consists of a central portion 3 with a boiler furnace wall 2 and a convection pass wall 7, a front portion 5 with a coal bunker 4, and a rear portion 6 enclosing an air pre-heating device (not shown). The boiler furnace wall 2 and the convection pass wall 7 and others are suspended to a large beam 8 that is located on the top of a boiler frame, so as to release the thermal expansion during the burning operation.
Accordingly, in a general construction process for the construction of the boiler furnace wall 2 and the convection pass wall 7, the large beam 8 is attached on top of the established boiler frame that is as high as 60 to 100 meters. After that, by hanging various parts for constructing the boiler furnace wall 2 and the convection pass wall 7 from the large beam 8, those walls are assembled from the upper portion toward lower portion in sequence. However, this construction process does not have high operating efficiency because of the dangerous operation in high altitude. Especially, as the boiler furnace wall 2 has a shape with large length in the lengthwise direction, with the process of constructing from upper portion toward lower portion, the necessary period for the installation work becomes long since the lower portion can not be assembled until the upper portion is assembled. Therefore, the largest factor to prolong the entire construction period for the boiler facility was the installation work for the boiler furnace wall 2.
In order to alleviate the problem, Japanese patent laid-open publication H5-240405 discloses a boiler furnace wall installation method dividing the boiler furnace wall 2 into three portions of an upper portion of boiler proper, left and right lower portions of boiler proper, suspending the upper portion of boiler proper to the desired position after assembling each portion at the bottom position inside of the boiler frame, then connecting the left and right lower portions of boiler proper by translating them to the upper portion of boiler proper. With this method, the construction period is expected to be shortened since there is less operation in high altitude and the upper portion of boiler proper and the lower portions of boiler proper can be assembled in parallel.
However, the method disclosed requires a large space in the boiler frame premise for assembling the upper and lower portions of boiler proper since the operation takes place at the bottom position inside of the boiler frame, which introduces large restriction to the establishment of the boiler frame. Additionally, as the upper and lower portions of boiler proper are assembled in suspension in the same way as the conventional method, a dedicated temporary suspension mechanism for each portion of boiler proper is required.